Sir John Fowler, 1st Baronet, KCMG, LLD (15 July 1817 – 20 November 1898) was an English civil engineer specialising in the construction of railways and railway infrastructure. In the 1850s and 1860s, he was engineer for the world's first underground railway, London's Metropolitan Railway, built by the "cut-and-cover" method under city streets. In the 1880s, he was chief engineer for the Forth Railway Bridge, which opened in 1890. Fowler's was a long and eminent career, spanning most of the 19th century's railway expansion, and he was engineer, adviser or consultant to many British and foreign railway companies and governments. He was the youngest president of the Institution of Civil Engineers, between 1865 and 1867, and his major works represent a lasting legacy of Victorian engineering.

Fowler's consulting work extended beyond Britain including railway and engineering projects in Algeria, Australia, Belgium, Egypt, France, Germany, Portugal and the United States. He travelled to Egypt for the first time in 1869 and worked on a number of, mostly unrealised, schemes for the Khedive,[1] including a railway to Khartoum in Sudan which was planned in 1875 but not completed until after his death.[7] In 1870 he provided advice to an Indian Government inquiry on railway gauges where he recommended a narrow gauge of 3 feet 6 inches (1.07 m) for light railways.[1][7] He visited Australia in 1886, where he made some remarks on the break of gauge difficulty.[8] Later in his career, he was also a consultant with his partner Benjamin Baker and with James Henry Greathead on two of London's first tube railways, the City and South London Railway and the Central London Railway.[1]

To avoid problems with smoke and steam overwhelming staff and passengers on the covered sections of the Metropolitan Railway, Fowler proposed a fireless locomotive. The locomotive was built by Robert Stephenson and Company and was a broad gauge2-4-0tender engine. The boiler had a normal firebox connected to a large combustion chamber containing fire bricks which were to act as a heat reservoir. The combustion chamber was linked to the smokebox through a set of very short firetubes. Exhaust steam was re-condensed instead of escaping and feed back to the boiler. The locomotive was intended to operate conventionally in the open, but in tunnels dampers would be closed and steam would be generated using the stored heat from the fire bricks.

Fowler's A class locomotive

The first trial on the Great Western Railway in October 1861 was a failure. The condensing system leaked, causing the boiler to run dry and pressure to drop, risking a boiler explosion. A second trial on the Metropolitan Railway in 1862 was also a failure, and the fireless engine was abandoned, becoming known as "Fowler's Ghost". The locomotive was sold to Isaac Watt Boulton in 1865; he intended to convert it into a standard engine but it was eventually scrapped.[12]

On opening, the Metropolitan Railway's trains were provided by the Great Western Railway, but these were withdrawn in August 1863. After a period hiring trains from the Great Northern Railway, the Metropolitan Railway introduced its own, Fowler designed, 4-4-0tank engines in 1864. The design, known as the A class and, with minor updates, the B class, was so successful that the Metropolitan and District Railways eventually had 120 of the engines in use and they remained in operation until electrification of the lines in the 1900s.[12]